Biometric properties, such as blood pressure, pulse rate and other cardiovascular properties, may be monitored using one or more of bio-impedance, optical, and ultrasonic sensor techniques. There are a number of challenges associated with the use of such non-invasive devices for monitoring cardiovascular and other biometric properties. Conventional sensors may need to be arranged close to the skin surface to detect targeted biological features and/or properties. For example, optical sensors may penetrate only a few millimeters below the skin, while ultrasonic sensors may penetrate several centimeters below the skin. Such short-range sensors may need to be positioned over or close to a subcutaneous biological structure (e.g., an artery, vein, bone, etc.) to obtain suitable measurements. However, it may be difficult to determine where to position such a conventional sensor on a subject. Some biological structures, such as arteries and muscle tissue, can move around within a volume of tissue, such that the location of the biological structure may change from one measurement to the next, further complicating accurate positioning of short-range biological sensors on a subject.